G

GRANT ED

Active Member
I remember reading on someones site that they used aftermarket aluminium gear legs on their RV saving 17 pounds. I have searched and searched but cannot find anywhere that sells such a product. Does anyone know of any that are availiable?
P.S for an RV-7.
 
Grant,

The aluminum gear legs folks have been talking about are for RV-8's, and are from Grove Aircraft http://www.groveaircraft.com/. They don't show any for RV-7's.
Question: with the gear layout of the 7 (swept back from engine mount), wouldn't using aluminum legs create more problems than the few pounds of weight saved? I'm thinking more flex and tire shimmy than the steel legs, less resilience to hard landings, etc. No flame intended, just wondering what the perceived benefit would be going to aluminum.
 
The only benefit with aluminium is weigh saving. Unlike steel aluminium has a finite fatigue life so careful attention must be paid to the design to prevent cracking. The swept back legs on the 7 would be harder to design than the 8 but I was just wondering if anyone had done it sucessfully.
 
Titanium

You could make the RV-4, RV-6, RV-7 gear legs out of Titanium, but they would be expensive. I believe the Harmon Rockets / F-1 use titanium gear legs and are like the RV tube-N-socket gear. You would save weight, have higher strength, stiffness could be less (larger deflections, some steels are stiffer) and weight about 40% less by volume. I am all for saving weight and any RV can be built light with steel gear legs. Not sure how many pounds you would save, 5 lbs, 10 lbs? Not sure it would be worth it. Many RV's come in way over what Van specs anyway, way over 10 lbs. Whlile other RV's come in at the low end of Vans weight spec. There are plenty of ways to keep 10lbs off and keep the weight down, but most builders tend to not watch the details that add up.

The weight difference between an O-320/O-360 is about 30lbs, the same as the difference between an O-360/IO-360(200hp). Wood or composite props are lighter than aluminum ones by 10-25lbs. Paint jobs can weigh 10lbs or they can weigh 30lbs. Did you prime every part inside and out. It all adds weight. The point is every one of the above items is a bigger saving than changing material of gear.

There are easier and cheaper ways to keep the empty weight down other than exotic metals for the gear. If you are going to add ever panel doo-dad, fancy interior and paint and a B747 inst panel with dual alternators/batteries, don't worry about weight, its going to be fat and 10 lbs will not help. Keep it light and build it per plans (except where the plans are wrong) :D

Cheers George
 
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